we consider {0,1}-matrices. for matrices a and b, we say a contains b as a configuration if there is a submatrix of a that is a column and row permutation of b. for instance, if a and b are incidence matrices of graphs g and h respectively, then a contains b as a configuration if and only if g contains h as a subgraph. in this talk, we study some extremal problems for matrices and hypergraphs (set systems).